Method and apparatus for an articulating drill

ABSTRACT

The present invention is an articulating hand power tool with a head portion including a head housing, a bit holder rotatably positioned within the head housing, and a bearing member operable to transfer a first axial force from the bit holder to the head housing. A frame is rotatably connected to the head portion for placement in a plurality of positions with respect to the head portion and operably connected to the head housing for receiving the first axial force transferred to the head housing. The tool further includes an articulating gear system for transferring rotational force generated by a motor to the bit holder at each of the plurality of positions.

This application claims the benefit of provisional U.S. PatentApplication No. 60/733,546, filed on Nov. 4, 2005. The disclosure ofthis provisional patent application is hereby totally incorporated byreference in its entirety.

FIELD OF THE INVENTION

The present invention relates to an electric hand tool and moreparticularly to an articulating power hand tool.

BACKGROUND

Electric drills are usually constructed as straight-drilling machines inwhich the drill spindle extends parallel to the motor shaft and axis ofthe housing and, for specific purposes, as angular-drilling machines inwhich the drill spindle is aligned at a right angle to the motor shaftand housing axis. In certain applications in which both straight andangular drilling must be carried out, as is the case in installations inwooden house construction, the two machines must be at hand forcontinuous alternation.

The use of a tool receptacle head serving as special accessory for aconventional drill to eliminate the need for two drills is known. By wayof example, DE 36 34 734 A1 discloses a drill that includes two separatehousing parts which are located opposite one another to define a hollowspace and which are guided along a diagonally extending dividing plane.One housing part carries a support for a drive shaft and the otherhousing part carries a support for a power take-off shaft which projectsout of the tool receptacle head and carries a drill chuck. The driveshaft and power take-off shaft are connected with one another by adouble cardan or universal joint so as to be rigid with respect totorsion relative to one another. One hollow-cylindrical housing part ofthe tool receptacle head is placed on the spindle neck of the drill andthe drill spindle of the drill is coupled with a driver by means of adouble edge. The driver sits on the drive shaft so as to be fixed withrespect to rotation relative to it. In the basic position of the twohousing parts, the axes of the drive and power take-off shafts are flushwith one another. Due to the relative rotation of the two housing parts,the power take-off shaft can be aligned in such a way that its axisencloses an acute or right angle with the axis of the drive shaft.

A standard drill can be re-tooled with this known tool receptacle headso as to form an angle drill which can also perform straight drilling.While such a separate tool receptacle head serving as attachment may besuited to the requirements of some hobbyists, it is not acceptable forprofessional machines.

U.S. Pat. No. 5,533,581 discloses a drill suitable for professional usethat includes a drill with a housing, an electric motor which isreceived in the housing, a motor shaft parallel to the housing axis, anda work spindle which is driven by the electric motor via a transmissiongearing. The housing is divided along a dividing plane for the purposeof switching from straight drilling to angular drilling and it isprovided that the front housing part containing a bearing for the workspindle and the rear housing part containing the electric motor canswivel relative to one another in such a way that the work spindleprojecting out of the front housing part can occupy any angle between 0degrees and 90 degrees or more relative to the motor shaft. A catch lockwhich can be unlocked and/or locked manually stops the two housing partsin the selected swivel position. A torsionally rigid transmission offorce from the motor shaft to the work spindle is realized in everyswivel position of the housing parts in the transmission gearing.

While the prior art drills are useful, they have various limitations.For example, drills are frequently exposed to impacts, both intentionaland accidental, on the bits which are held by the drills. The prior artdrills generally transmit these impact forces through the gearingmechanisms which allow for the relative positioning of the work spindlewith respect to the motor shaft. Accordingly, the gears must be designedto absorb the impact forces. Such gears may increase the weight of thedrill and increase the size of the forward section of the drill.Increased weight increases the fatigue experienced by a user,particularly users who use the tool infrequently. Moreover, theadditional bulk of the drill reduces the usefulness of the tool inconfined areas.

Additionally, the locking mechanisms used to restrict articulation inprior articulating drill systems may be difficult to use or susceptibleto accidental activation. Furthermore, in certain known devices thearticulating gear mechanism is exposed allowing contaminants into themechanism as well as presenting a safety concern as clothing orappendages may be caught by revolving gears.

What is needed is an articulating power hand tool which protectsinternal components from damage resulting from axial impact. It would bebeneficial to further protect the internal components from contaminationand reduce the potential for external items becoming entrapped by theinternal components.

What is further needed is an articulating power hand tool with a reducedforward section and a compact articulating system to allow for use ofthe tool in confined areas.

What is also needed is an articulating power hand tool having a latchmechanism exhibiting increased strength and which further reduces thepotential of accidental manipulation.

SUMMARY

The present invention is an articulating hand power tool. In oneembodiment, the tool includes a head portion including a head housing, abit holder rotatably positioned within the head housing, and a bearingmember operable to transfer a first axial force from the bit holder tothe head housing. A frame is rotatably connected to the head portion forplacement in a plurality of positions with respect to the head portionand operably connected to the head housing for receiving the first axialforce transferred to the head housing. The tool further includes anarticulating gear system for transferring rotational force generated bya motor to the bit holder at each of the plurality of positions.

One method of transferring axial forces in an articulating power tool inaccordance with the invention includes transferring an axial force froma bit holder rotatably positioned within a head housing of a tool to abearing member, transferring the axial force from the bearing member tothe head housing, and transferring the axial force from the head housingto a main housing, wherein the head housing is rotatable with respect tothe main housing.

These and other advantages and features of the present invention may bediscerned from reviewing the accompanying drawings and the detaileddescription of the preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention may take form in various system and methodcomponents and arrangement of system and method components. The drawingsare only for purposes of illustrating exemplary embodiments and are notto be construed as limiting the invention.

FIG. 1 shows a perspective view of an articulating drill incorporatingfeatures of the present invention;

FIG. 2 shows a side elevational view of the articulating drill of FIG. 1with the rechargeable battery pack removed;

FIG. 3 shows a perspective view of the articulating drill of FIG. 1 withthe battery pack, a portion of the main housing cover, and a portion ofthe head housing removed and a bit in the bit holder;

FIG. 4 shows a cross-sectional view of the head portion, thearticulating gear system and the planetary gear system of thearticulating drill of FIG. 1;

FIG. 5 shows an exploded perspective view of the head portion, includingan automatic spindle lock system, of the articulating drill of FIG. 1;

FIG. 6 shows a top plan view of the head portion of the drill of FIG. 1with some components located within bays in the head housing;

FIG. 7 shows a top plan view of a bracket used to support an outputpinion shaft in the articulating drill of FIG. 1;

FIG. 8 shows a side plan view of the bracket of FIG. 7;

FIG. 9 shows a top elevational view of the planetary gear section,articulating section and head portion of the articulating drill of FIG.1 with the main housing and a portion of the head housing removed;

FIG. 10 shows a side elevational view of the articulating gear system ofthe articulating drill of FIG. 1 including a bevel gear and two piniongears;

FIG. 11 is a perspective view of a portion of the head housing of thedrill of FIG. 1 with a plurality of teeth in a well which are formedcomplimentary to teeth on the articulation button;

FIG. 12 shows a perspective view of the articulating button of thearticulating drill of FIG. 1;

FIG. 13 shows a perspective view of the bottom of the articulatingbutton of FIG. 12;

FIG. 14 shows a partial top elevational view of the inner surface of theouter housing of the articulating drill of FIG. 1 with teeth formedcomplimentary to the teeth on the articulation button and a hole forreceiving a raised portion of the articulating button;

FIG. 15 shows a top elevational view of the inner surface of the outerhousing of the articulating drill of FIG. 1;

FIG. 16 shows a partial plan view of the articulating drill of FIG. 1with the head portion aligned with the main housing portion and withouta dust lid;

FIG. 17 shows a partial plan view of the articulating drill of FIG. 1with the head portion aligned with the main housing portion with a dustlid;

FIG. 18 shows a side elevational view of the articulating drill of FIG.18 with the head portion rotated to an angle of 90 degrees from the mainhousing portion of the drill and a portion of the main housing portionremoved to show the position of the dust lid of FIG. 17;

FIG. 19 shows a side elevational view of the articulating drill of FIG.18 with the head portion rotated to an angle of 180 degrees from themain housing portion of the drill and a portion of the main housingportion removed to show the position of the dust lid of FIG. 17;

FIG. 20 shows a detail view of the dust lid of FIG. 19;

FIG. 21 shows a perspective view of the articulating drill of FIG. 1with the variable speed trigger switch, clutch control and a portion ofthe main housing removed;

FIGS. 22 a, 22 b and 22 c show various views of a printed circuit boardof the articulating drill of FIG. 1 in accordance with principles of theinvention;

FIG. 23 shows a perspective view of the articulating drill of FIG. 21with a collapsible boot with an internal reflective surface installedover a light generator and a light sensor;

FIG. 24 shows a schematic/block diagram of the drill of FIG. 1incorporating an optical switch for motor speed control;

FIG. 25 shows a side elevational view of a drill bit in the form of ascrew driver bit that may be used with the articulating drill of FIG. 1;

FIG. 26 shows a cross-sectional view of the drill bit of FIG. 25 beinginserted into the articulating drill of FIG. 1;

FIG. 27 shows a cross-sectional view of the drill bit of FIG. 25inserted into the articulating drill of FIG. 1;

FIG. 28 shows a partial top elevational view of a bevel gear inaccordance with principles of the invention with two pinion gears at a90 degree spacing;

FIG. 29 shows a partial top elevational view of the bevel gear of FIG.28 with the two pinion gears at a 180 degree spacing;

FIG. 30 shows an electrical diagram/schematic of a powered tool thatdynamically brakes the tool motor using a motor interface circuit havinga half bridge to provide vibratory feedback to the operator that thetorque limit has been reached;

FIG. 31 shows an electrical diagram/schematic of a circuit that may beused with the drill of FIG. 1 which dynamically brakes the drill motorusing a motor interface circuit having a full H-bridge circuit toprovide vibratory feedback to the operator that the torque limit hasbeen reached; and

FIGS. 32A and 32B show an electrical diagram/schematic of a powered toolthat provides solid state motor speed control in correspondence with avariable speed signal from an optical switch and that dynamically brakesthe motor to indicate a torque limit has been reached.

DESCRIPTION

An articulating drill generally designated 100 is shown in FIG. 1. Inthe embodiment of FIG. 1, the drill 100 includes a main housing portion102 and a head portion 104. The main housing portion 102 houses a motorand associated electronics for control of the drill 100. The mainhousing portion 102 includes a battery receptacle for receiving arechargeable battery pack 106 as is known in the art. In one embodiment,the rechargeable battery pack 106 comprises a lithium-ion battery. Thebattery pack 106 is removed by depression of the battery release tabs108. FIG. 2 shows the drill 100 with the battery pack 106 removed. Thedrill 100 may alternatively be powered by an external power source suchas an external battery or a power cord.

A variable speed trigger switch 110 controls the speed at which themotor rotates. The direction of rotation of the motor is controlled by areversing button 112 which slides within a finger platform 114.Ventilation openings 116 allow for cooling air to be circulated aroundthe motor inside of the main housing 102. A clutch control 118 sets themaximum torque that may be generated when using the drill 100. At theposition shown in FIG. 1, the clutch control 118 is at the highestsetting or drill mode. At the highest setting, the clutch is disabled toprovide maximum torque. By sliding the clutch control 118 downwardlyfrom the position shown in FIG. 1, a user may set a desired torque limitthat is allowed to be generated by the drill 100 as discussed in moredetail below. Accordingly, at settings other than the highest setting, atorque above the setting of the clutch control 118 causes the clutch toactivate.

The main housing portion 102 also includes an articulation button 120and a plurality of angle reference indicators 122 molded onto the outersurface 124 of the main housing 102. In the embodiment of FIG. 1, thereare five angle reference indicators 122 used to identify five angularpositions in which the head portion 104 may be placed.

The head portion 104 includes a collet locking device 126 and an angleindicator 128. The angle at which the head portion 104 is positioned isindicated by the angle reference indicator 122 with which the angleindicator 128 is aligned. As shown in FIG. 1, the head portion 104 is ata 90 degree angle with respect to the main housing portion 102. In FIG.2, the head portion 104 is axially aligned with the main housing portion102. Although the embodiment of FIGS. 1 and 2 has five angle referenceindicators 122, there may be additional or fewer angle referenceindicators 122 and corresponding angles at which the head portion 104may be placed with respect to the main housing portion 102.

Referring now to FIGS. 3-6, the collet locking device 126 is locatedaround a bit holder 130 which is in turn supported by a ball bearing 132that is fixed within a bearing pocket 134 of the head housing 136. Thecollet locking device 126 includes a sleeve 138 with recesses 140. Aspring 142 is positioned about the bit holder 130. The bit holder 130includes a hole 144 which receives a cylinder pin 146 and recesses 148which receive steel balls 150.

The bearing 132 abuts the head housing 136 of the head portion 104 atthe outer rear periphery of the bearing 132. More specifically, thebearing 132 abuts a flange 152. In this embodiment, the flange 152 iscontinuous about the housing 136, although a flange may alternatively bein the form of a plurality of fins located about the inner portion ofthe housing 136.

The bit holder 130 is operably coupled to a drive collet 154 which is inturn connected to an output pinion shaft 156 through a drive plate 158which is fixedly attached to the output pinion shaft 156. A lock ring160 surrounds the drive collet 154 and three locking pins 162. The lockring 160, the drive collet 154, the drive plate 158, and the lockingpins 162 all comprise an automatic spindle lock system such that theoutput bit holder 130 can only be driven from the pinion side as knownin the art. When driven from the bit side, i.e., when the tool 100 isused as a manual screwdriver, the spindle lock system keeps the outputpinion shaft 156 from rotating thus facilitating use of the tool 100 asa manual screwdriver. In an alternative embodiment, a manuallymanipulated locking device may be used.

A pinion gear 164 is located at the opposite end of the output pinionshaft 156 from the drive plate 158. One end of the output pinion shaft156 is maintained in axial alignment by a bearing 166 which fits withinbearing pocket 168. The opposite end of the output pinion shaft 156 issupported by a sleeve 170. The sleeve 170 is supported on one side by aflange 172 on the head housing 136. On the opposite side, the sleeve 170is supported by a bracket 174 also shown in FIGS. 7 and 8.

The bracket 174 includes a support area 176 configured complimentary toa portion of the sleeve 170. Two connection arms 178 are configured tobe attached to the head housing 136 as shown in FIG. 9. The bracket 174eliminates the need to provide a matching flange for flange 172 moldedinto the opposite side of the head housing 136. The elimination of theneed for an opposing flange allows for a significant increase in designfreedom as the space requirements for the support structure for thesleeve 170 are reduced. The bracket 174 may be stamped from W108 steelto provide the needed rigidity and strength.

Referring now to FIG. 10, the pinion gear 164 forms a portion of anarticulating gear system 180. The articulating gear system 180 furtherincludes a bevel gear 182 which is engaged at the output portion of thearticulating gear system 180 with the pinion gear 164 and furtherengaged on the motor portion by pinion gear 184. The shaft 186 of thebevel gear 182 is supported at one end within a hole 188 (see FIG. 4) ofthe frame 190. The frame 190 is made from a zinc and aluminum alloyZA-8. This material provides a sufficiently low coefficient of frictionto ensure relatively small frictional forces exist between the shaft 186and the frame 190.

The shaft 186 is radially and axially supported at the opposite end by aball bearing 192 supported by the frame 190. At this end of the shaft186, however, comparatively larger forces are generated than at the endof the shaft 186 inserted within the hole 188. More specifically, asshown in FIG. 10, both pinion gear 164 and pinion gear 184 are locatedon the same side of the bevel gear 182. Accordingly, as the articulatinggear system 180 rotates, a force is generated on the bevel gear 182 inthe direction of the arrow 194 toward the base 196 of the bevel gear182. This force acts to disengage the bevel gear 182 from the piniongear 164 and the pinion gear 184. With this increased force acting uponthe bevel gear 182, an unacceptable amount of axial force would betransmitted to the bearing 192. Accordingly, a thrust bearing 198 isprovided to protect the ball bearing 192 and to provide a low frictionsupport for the base 196 of the bevel gear 182. The thrust bearing 198is made of a material with an acceptably low coefficient of frictionsuch as oil impregnated bronze commercially available from McMaster Carrof Chicago, Ill. Accordingly, the friction generated at the base 196 ofthe bevel gear 182 is maintained within acceptable levels.

Referring again to FIG. 4, the pinion gear 184 is fixedly attached to aplanetary gearbox shaft 200 which receives torque from a planetary gearsystem generally indicated as reference numeral 202. The planetary gearsystem 202 receives torque from a motor as is known in the art. Theplanetary gear system 202 is located within a planetary gear housing 204which is inserted partially within the frame 190. This arrangementallows for the planetary gear system 202 to be separately manufacturedfrom the other components while simplifying assembly of the planetarygear system 202 with the other components. This modularity furtherallows for alternative gearings to be provided in the planetary gearsystem 202 while ensuring a proper fit with the other components.

Generally, it may be desired to provide a simple friction fit betweenthe planetary gear housing 204 and the frame 190. In the embodiment ofFIG. 4, however, the articulating gear system 180 generates an axialforce along the planetary gearbox shaft 200. This axial force acts todisengage the planetary gear housing 204 from the frame 190.Accordingly, pins 206 and 208 which extend through both the planetarygear housing 204 and the frame 190 are provided. The pins 206 and 208ensure the planetary gear housing 204 does not become detached from theframe 190 during operation of the drill 100. Alternatively, theplanetary gear housing 204 and the frame 190 may be formed as anintegral unit.

Continuing with FIG. 4, the frame 190 is configured to slidingly matewith the head housing 136. To this end, the head housing 136 includes ashroud portion 210 which is complimentarily formed to the frame 190about the ball bearing 192. The head housing 136 further includes arecess 212 which is configured to receive the portion of the frame 190which defines the hole 188. Also shown in FIG. 4 is a well 214 whichincludes a plurality of teeth 216 shown in FIG. 11.

With further reference to FIGS. 12-14, the well teeth 216 are formedcomplimentary to a plurality of teeth 218 which are formed in thearticulation button 120. The articulation button 120 includes a raisedcenter portion 220 which is configured to fit within a hole 222 in themain housing portion 102. The teeth 218 of the articulation button 120are further configured to mesh with a plurality of teeth 224 formed onthe inner side of the main housing portion 102 around the hole 222. Thearticulation button 120 also includes a spring receiving well 226 on theside of the articulation button 120 facing the well 214. When assembled,a spring (not shown) is located within the well 214 and extends into thespring receiving well 226 forcing the raised center portion 220 of thearticulation button 120 toward a position wherein the articulationbutton 120 projects into the hole 222.

Referring to FIGS. 4 and 15, the frame 190 is supported axially in themain housing portion 102, which in this embodiment is made of plastic,by a rib 228. The rib 228 lies beneath a fin 230 of the frame 190 whenthe frame 190 is installed in the main housing portion 102 as shown inFIG. 3. The planetary gear system 202 is mechanically secured to a motor232 which is itself electrically connected to a printed circuit board234 which in turn is electrically connected to a battery contact holder236. The contact holder 236 mates with battery pack receptacles on thebattery pack 106 and transmits battery power to the electronic circuitboard 234 through lead wires (not shown). Another pair of lead wires(not shown) extend from the circuit board 234 to the motor terminals 238to deliver the required voltage level to the motor 232.

Referring now to FIG. 5, a gap 240 is provided in the portion of thehead housing 136 surrounding the bevel gear 182 which allows the headhousing 136 to be rotated with respect to the main housing portion 102while the pinion gear 164 remains engaged with the bevel gear 182. Whenthe head portion 104 is axially aligned with the main housing portion102, however, the gap 240 is exposed as shown in FIG. 16. Thearticulating gear system 180 is thus exposed allowing contaminantsaccess to the articulating gear system 180 which could foul thearticulating gear system as well as presenting a safety concern sinceclothing, fingers or hair could become enmeshed in the articulating gearsystem 180. Accordingly, a floating dust lid 242 shown in FIG. 17 isused to prevent contamination of the articulating gear system 180 and toavoid exposure of moving gears to an operator through the gap 240,particularly when the head housing 136 is axially aligned with the mainhousing portion 102 as shown in FIG. 17.

The dust lid 242 is located in a channel 244 defined by the main housingportion 102 and the head housing 136 as shown in FIGS. 18-20. Theposition of the dust lid 242 at the lower portion (as depicted in FIGS.18 and 19) of the channel 244 is constrained either by a movable dustlid travel limiter 246 positioned on the head housing 136, shown mostclearly in FIGS. 11 and 20, or by a portion 248 of the frame 190. Theposition of the dust lid 242 at the upper portion of the channel 244 isconstrained either by a neck portion 250 of the head housing 136 or by alip 252 in the main housing portion 102.

Referring now to FIGS. 3, and 21-23, the clutch control 118 ismechanically interfaced with a linear potentiometer 254 on the circuitboard 234. Also located on the circuit board 234 is a light sensor 256which is covered by a collapsible rubber boot 258 which is in turnmechanically fastened to the variable speed trigger 110. A reflectivesurface 260 (see FIG. 24) is located on the inside of the rubber boot258. A plastic spring locating member 262 which is mechanically securedto the circuit board 234 serves to locate and support a spring 264 whichis mechanically fastened to the variable speed trigger 110. The spring264 biases the variable speed trigger 110 in a direction away from thecircuit board 234 about a pivot 266. The circuit board 234 also containsa two position slide switch 268 which is mechanically interfaced to thereversing button 112.

Manipulation of the variable speed trigger 110 about the pivot 266changes the position of the reflective surface 260 relative to the lightsensor 256 to produce a variable speed control signal. While theembodiment of tool 100 incorporates an optical signal generator andreceiver for provision of a variable speed control signal, such a toolmay alternatively use a pressure transducer, a capacitive proximitysensor, or an inductive proximity sensor. In these alternativeembodiments, a pressure sensing switch for generating the variable motorspeed control signal may include a pressure transducer for generating avariable speed control signal that corresponds to a pressure applied tothe pressure transducer directly by the operator or through anintermediate member such as a moveable member that traverses thedistance between the stop position and the full speed position.

An embodiment of the variable motor speed control signal implementedwith a capacitive proximity sensor may include a capacitive sensor thatgenerates a variable speed control signal that corresponds to anelectrical capacitance generated by the proximity of an operator'sfinger or moveable member's surface to the capacitive sensor. Anembodiment implemented with an inductive proximity sensor generates avariable speed control signal that corresponds to an electricalinductance generated by the proximity of an operator's finger ormoveable member's surface to the inductive sensor.

Referring to FIG. 23, the variable speed control circuit 270 of the tool100 is schematically shown. The variable speed control circuit 270includes a power contact 272 which is operably connected to the variablespeed trigger switch 110. An optical signal generator 274 is coupled tothe battery 106 and arranged on the circuit board 232 such that lightemitted from the optical signal generator 274 is directed toward thereflective surface 260 of the variable speed trigger switch 110 anddirected toward the light sensor 256.

The light sensor 256 and the optical signal generator 274 may be locatedin the same housing or each may be within a separate housing. When thetwo components are located in the same housing, the light generator andsensor may emit and receive light through a single sight glass in thehousing. Alternatively, each component may have a separate sight glass.An integrated component having the light generator and sensor in asingle housing is a QRD1114 Reflective Object Sensor available fromFairchild Semiconductor of Sunnyvale, Calif. Such a housing issubstantially smaller than a potentiometer that has a wiper, whichtraverses approximately the same distance as the trigger traverses fromthe stop to the full speed position.

The optical signal generator 274 and the light sensor 256 may be aninfrared light emitter and an infrared light receiver. In an alternativeembodiment, an IR transceiver may be contained within a flexible dustcover that is mechanically fastened to the back of the variable speedtrigger switch. In such an embodiment, the inside of the cover in thevicinity of the moveable trigger reflects the optical signal to thereceiver for generating the speed control signal.

Control of a tool incorporating the light sensor 256 may be adverselyaffected by external energy sources such as the sun. Accordingly, in oneembodiment, the collapsible boot or dust cover 258 is made from anopaque material or coated with an opaque material such that energy fromthe sun which may leak past the housing and trigger arrangement does notaffect the signal received by the light sensor 256. Alternatively, alight sensor that is sensitive to a specific frequency band may be usedwith a device which shields the light sensor from only that specificfrequency band. In further embodiments, other circuitry or coding whichuniquely identifies the energy from the reflected signal frominterfering energy may be used.

The light sensor 256 is an optical transistor having a collector 276coupled to the battery pack 106 through the contact 272 and an emitter278 coupled to electrical ground though a voltage divider 280 and acapacitor 282. A timing signal generator 284 receives voltage from thevoltage divider 280. In the tool 100, the timing signal generator 264 isa commonly known 555 timer, although other timing signal generators maybe used.

The output of the timing signal generator 264 is coupled to a gate 286of a MOSFET 288 that has a drain 290 coupled to one of the motorterminals 238 and a source 292 coupled to electrical ground. The othermotor terminal 238 is coupled to the battery pack 106 through thecontact 272. A freewheeling diode 294 is coupled across the motorterminals 238. A bypass contact 296, which is operatively connected tothe variable speed trigger switch 110, is located in parallel to theMOSFET 288 between the motor terminal 238 and electrical ground and abrake contact 298 is in parallel with the freewheeling diode 294.

Operation of the drill 100 is explained with initial reference to FIGS.24-26. The collet locking device 126 is configured to operate with bitssuch as the screw driver bit 300 shown in FIG. 24. The screw driver bit300 and the bit holder 130 are complimentarily shaped. In this example,both the screw driver bit 300 and the bit holder 130 are generallyhexagonal in shape, although alternative shapes may be used. The screwdriver bit 300 has a diameter slightly less than the bit holder 130 sothat it may fit within the bit holder 130. The screw driver bit 300includes a notched area 302 and a tail portion 304.

Initially, the sleeve 138 is moved to the right from the position shownin FIG. 4 to the position shown in FIG. 26 thereby compressing thespring 142. As the sleeve 138 moves, recesses 140 in the sleeve 138 arepositioned adjacent to the recesses 148 in the bit holder 130. Then, asthe screw driver bit 300 is moved into the bit holder 130, the tailportion 304 forces the steel balls 150 toward the recesses 140 and outof the channel of the bit holder 130, allowing the tail portion 304 tomove completely past the steel balls 150.

At this point, the notched area 302 is aligned with the recesses 148.The sleeve 138 is then released, allowing the spring 142 to bias thesleeve 138 onto the bit holder 130 which is to the left from theposition shown in FIG. 27. As the sleeve 138 moves, the recesses 140 aremoved away from the recesses 148 thereby forcing the steel balls 150partially into the channel of the bit holder 130 as shown in FIG. 27.Movement of the steel balls 150 into the channel of the bit holder 130is allowed since the notched area 302 is aligned with the recesses 148.At this point, the bit 300 is firmly held within the bit holder 130.

The head housing 136 is then articulated to a desired angle with respectto the main housing portion 102. Initially, the spring (not shown) inthe spring receiving well 226 forces the articulation button 120 toextend into the hole 222. Accordingly, the teeth 218 of the articulationbutton 120 are meshed with the teeth 224 in the main housing portion 102as well as the teeth 216 in the well 214 of the head housing 136,thereby angularly locking the articulation button 120 (and the headhousing 136) with the main housing portion 102. Additionally, the dustlid 242 is constrained at the upper portion of the channel 244 by theneck portion 250 of the head housing 136 and at the lower portion of thechannel 244 by the portion 248 of the frame 190 as shown in FIG. 18.

The operator then applies force to the articulation button 120 causingthe spring (not shown) to be depressed thereby disengaging the teeth 218from the teeth 224. Thus, even though the teeth 218 remain engaged withthe teeth 216, the head portion 104 is allowed to pivot with respect tothe main housing portion 102. As the head portion 104 is articulated,for example, from the position shown in FIG. 1 to the position shown inFIG. 2, the pinion gear 164 articulates about the bevel gear 182. By wayof example, FIG. 28 shows the positions of the pinion gears 164 and 184with respect to the bevel gear 182 when the drill 100 is in theconfiguration shown in FIG. 1. In this configuration, the pinion gear164 is approximately 90 degrees away from the pinion gear 184 about theperimeter of the bevel gear 182. As the head portion 104 is articulatedin the direction of the arrow 306, the pinion gear 164 articulates aboutthe bevel gear 182 in the same direction. Thus, when the head portion104 is aligned with the main housing portion 102, the pinion gear 164 ispositioned on the bevel gear 182 at a location 180 degrees away from thepinion gear 184 as shown in FIG. 29.

Throughout this articulation, the pinion gears 164 and 184 remainengaged with the bevel gear 182. Accordingly, the bit holder 130 may berotated by the motor 232 as the head housing 136 is articulated.Additionally, the articulation of the head housing 136 causes themovable dust lid travel limiter 246 to contact the dust lid 242 and pushthe dust lid 242 along the channel 244. Thus, the dust lid 242, which isconfigured to be wider than the gap 240 as shown in FIG. 17, restrictsaccess from outside of the drill 100 to the articulating gear system180.

When the articulating drill 100 is rotated to the desired location, theoperator reduces the force applied to the articulating button 120. Thespring (not shown) in the spring receiving well 226 is then allowed toforce the articulation button 120 away from the well 214 until thearticulation button 120 extends through the hole 222. Accordingly, theteeth 218 of the articulation button 120 are meshed with the teeth 224in the main housing portion 102 as well as the teeth 216 in the well 214of the head housing 136, thereby angularly locking the articulationbutton 120 (and the head housing 136) with the main housing portion 102.

The desired direction of rotation for the bit 300 is then established byplacing the reversing button 112 in the position corresponding to thedesired direction of rotation in a known manner. Rotation isaccomplished by moving the variable speed trigger switch 110 about thepivot 266 to close the power contact 272. The closing of the contact 272completes a circuit allowing current to flow to the optical signalgenerator 274 causing light to be emitted.

The emitted light strikes the reflective surface 260 and a portion ofthe light is reflected toward the light sensor 256. The amount of lightreflected by the reflective surface 260 increases as the reflectivesurface 260 is moved closer to the light sensor 256. The increased lightsensed by the light sensor 256 causes increased current to be conductedby the light sensor 256 and the flow of current through the light sensor256 causes current to flow from the collector 276 to the emitter 278.Thus, as the intensity of the light impinging on the light sensor 256increases, the current conducted by the light sensor 256 increases. Thisincrease in current causes the voltage level presented by the voltagedivider 280 to the timing signal generator 284 to increase. Theincreased signal is the variable speed signal and it causes the timingsignal generator 284 to generate a timing signal in a known manner. Inthe depicted drill 100, the timing signal generator 284 is a commonlyknown 555 timer, although other timing signal generators may be used.

The timing signal generator 284 generates a timing pulse having alogical on-state that corresponds to the level of the variable speedsignal. This signal is presented to the gate 286 of the MOSFET 288. Whenthe signal present at the gate 286 is a logical on-state, the MOSFET 288couples one of the motor terminals 238 to ground while the other motorterminal 238 is coupled to battery power through the main contact 272.Thus, when the variable speed trigger switch 110 reaches a positionwhere the light sensor 256 begins to detect reflected light and generatea variable speed signal, the timing signal generator 284 begins togenerate a signal that causes the MOSFET 288 to couple one of the motorterminals 238 to ground. Once this occurs, current begins to flowthrough the MOSFET 288 and the motor 232 begins to rotate in thedirection selected by the reversing button 112.

The freewheeling diode 294 causes appropriate half-cycles of the currentin the windings of the motor 232 to flow out of the motor 232, throughthe diode 294, and back into the motor 232 when the MOSFET 288 does notconduct in response to the timing signal being in the off-state. Thisaction is known as freewheeling and is well known.

When the variable speed trigger 110 is in the full speed position, thetiming signal is predominantly in the on-state and the bypass contact296 closes. The closing of the bypass contact 296 enables the batterycurrent to continuously flow through the motor 232 so that the motor 232rotates at the highest speed.

When rotation is no longer desired, the operator releases the variablespeed trigger switch 110 and the spring 264 causes the variable speedtrigger switch 110 to rotate about the pivot 266 causing the bypasscontact 296 to open. Additionally, the brake contact 298 closes therebycoupling the motor terminals 238. The coupling of the two motorterminals 238 to one another through the brake contact 298 enablesdynamic braking of the motor.

The electronic control of the tool 100 thus requires less space for thecomponents that generate the variable speed signal than prior artcontrol systems. Because the distance traveled by the variable speedtrigger switch 110 does not have to be matched by the light signalgenerator 274 and the light sensor 256, considerable space efficiency isgained. Additionally, the light signal generator 274 and the lightsensor 256 do not require moving parts, so reliability is improved aswell. Advantageously, the light signal generator 274 and the lightsensor 256 may be mounted on the same printed circuit board 234 on whichthe timing signal generator 284 is mounted.

As the drill 100 is operated, the bit 300 is subjected to axial forces.The axial forces may result from, for example, pressure applied by theoperator or by an impact on the bit. In either instance, thearticulating gear system 180 is protected from damage without increasingthe bulk of the components within the articulating gear system 180. Thisis accomplished by directing axial forces from the bit 300 to the mainhousing portion 102 of the drill 100 while bypassing the articulatinggear system. With initial reference to FIG. 27, an impact on the bit 300tends to move the bit 300 further into the drill 100, or to the left asdepicted in FIG. 27. In prior art designs, not only could such a forcedamage the gear system, but the steel balls used to retain the bitwithin the bit holder would frequently jam necessitating replacement ofthe collet locking device.

As shown in FIG. 27, however, the cylinder pin 146 is positioned suchthat the tail portion 304 of the bit 300 will contact the cylinder pin146 before the wall of the notched area 302 contacts the steel balls150. Thus, an axial impact will not cause the steel balls 150 to jam. Ofcourse, the cylinder pin 146 must be made from a material sufficient towithstand the axial impact. In accordance with one embodiment, thecylinder pin 146 is made of AISI 4135 steel.

Referring now to FIG. 4, in the event of an axial impact, the force istransferred from the cylinder pin 146 to the to the bit holder 130. Theaxial force is transmitted from the bit holder 130 to the bearing 132which is located within the bearing pocket 134. Accordingly, the axialforce is transferred into the flange 152 (see also FIG. 5) of the headhousing 136. The head housing 136 in this embodiment is made fromaluminum alloy A380 so as to be capable of receiving the forcetransmitted by the bearing 132. The force is subsequently transferred tothe frame 190 and into the rib 228 of the main housing portion 102.

More specifically, two paths for the transfer of axial forces areprovided around the articulating gear system 180. The first pathpredominantly transfers axial forces when the head housing 136 isaxially aligned with the main housing portion 102. In thisconfiguration, axial forces pass from head housing 136 to the frame 190primarily through the recess 212 where the head housing 136 engages theframe 190 about the hole 188 (see FIG. 4) and at the shroud portion 210where the head housing 136 engages the frame 190 outwardly of the baseof the bevel gear 196.

The second path predominantly passes axial forces when the head housing136 is at a ninety degree angle with respect to the main housing portion102. In this configuration, axial forces are again transferred from thecylinder pin 146 to the to the bit holder 130. The axial forces thenpass primarily from the teeth 216 in the well 214 of the head housing136 to the teeth 218 on the articulation button 120 and then to theteeth 224 in the main housing portion 102.

When the head housing 136 is neither completely aligned with the mainhousing portion 102 or at a ninety degree angle with respect to the mainhousing portion 102, axial forces generally pass through both of theforegoing pathways. Accordingly, the effect of axial forces on thearticulating gear system 180 of the drill 100 are reduced. Because thearticulating gear system 180 is thus protected, the articulating gearsystem 180 may be constructed to be lighter than other articulating gearsystems.

In one embodiment, a printed circuit board which may be used in thedrill 100 or another power tool includes a circuit that providesvibratory feedback to the operator as shown in FIG. 30. The vibratoryfeedback circuit 308 includes a microcontroller 310, a driver circuit312, and motor interface circuit 314. The driver circuit 312 in thisembodiment is an integrated circuit that generates driving signals for ahalf-bridge circuit from a single pulse width modulated (PWM) signal, atorque limit indicating signal, which may be the same signal as the PWMsignal, and a motor direction control signal. The driver circuit 312 maybe a half bridge driver, such as an Allegro 3946, which is availablefrom Allegro Microsystems, Inc. of Worcester, Mass.

The output of the driver circuit 312 is connected to a motor 316 throughtwo transistors 318 and 320 which may be MOSFETs, although other typesof transistors may be used. The transistor 318 may be connected toeither terminal of the motor 316 through switches 322 and 324 while thetransistor 320 may be connected to either terminal of the motor 316through switches 326 and 328. A shunt resistor 330 is coupled betweenthe transistor 320 and electrical ground. The high potential side of theresistor 330 is coupled to the microcontroller 310 through an amplifier332. A power source 334 is also provided in the vibratory feedbackcircuit 308 and a maximum torque reference signal is provided from atorque reference source 336 which may be a linear potentiometer such asthe linear potentiometer 254.

The half-bridge control of the motor 316 eliminates the need for afreewheeling diode because the driver circuit 312 generates motorinterface circuit signals for selectively operating the motor interfacecircuit 314 to control the rotational speed of the motor 316. Morespecifically, a variable speed control signal 338, which may be from atrigger potentiometer or the like, is provided to the microcontroller310 for regulation of the rotation of the motor 316 by themicrocontroller 310. Based upon the variable speed control signal 338,the microcontroller 310 generates a PWM signal that is provided to thedriver circuit 312. In response to the PWM signal, the driver circuit312 turns transistors 318 and 320 on and off.

During typical operations, the transistor 318 is the complement of thetransistor 320 such that when the transistor 320 is on, the transistor318 is off. The rate at which the transistor 320 is turned on and offdetermines the speed of motor 316. The direction of rotation of themotor 316 is determined by the position of the switches 322, 324, 326and 328 under the control, for example, of a reversing switch.

The current through the motor 316 is provided through the transistor 320and the resistor 330 to electrical ground when the transistor 320 is inthe on-state. This current is related to the torque at which the motor316 is operating. Thus, the voltage at the high potential side of theresistor 330 is related to the torque on the motor 316. This motortorque signal is amplified by the amplifier 332 and provided to themicrocontroller 310. The microcontroller 310 compares the amplifiedmotor torque signal to the torque limit signal established by the torquereference source 336. The torque limit signal, which may alternativelybe provided by a different type of torque limit signal generator,provides a reference signal to the microcontroller 310 that correspondsto a current through the motor 316 that represents a maximum torquesetting for the motor 316.

In response to the microcontroller 310 receiving a motor torque signalthat exceeds the maximum torque setting for the motor 316, themicrocontroller 310 generates a braking signal that is provided to thedriver circuit 312. In response to the braking signal, the drivercircuit 312 turns transistor 320 to the off-state and leaves transistor318 in the on-state. This enables regenerative current to dynamicallybrake the rotation of the motor 316.

As dynamic braking occurs, the torque experienced by the motor 316decreases until the sensed torque is less than the maximum torquesetting for the motor 316. The microcontroller 310 then returns thetransistor 320 to the on-state, thereby rotating the motor 316 andincreasing the torque experienced by the motor 316. In this manner, themotor 316 alternates between rotating and dynamically braking whichcauses the tool to vibrate and alert the operator that the torque limithas been reached. An effective frequency for providing this vibratoryfeedback is 30 Hz. The torque limit indicating signal that results inthis operation continues as long as the trigger remains depressed.Alternatively, the microcontroller may be programmed to generate thetorque limit indicating signal for a fixed duration and then to stop toreduce the likelihood that the motor will be overpulsed.

In one embodiment, vibratory feedback is provided for the drill 100 withthe circuit shown in FIG. 31. The vibratory feedback circuit 340includes a microprocessor 342, an H-bridge driver circuit 344 and amotor interface circuit 346. Four MOSFETs 348, 350, 352 and 354 controlpower to the motor 232 from the rechargeable battery pack 106 under thecontrol of the H-bridge driver circuit 344. A shunt resistor 356 isprovided between the MOSFETs 352 and 354 and electrical ground. Thesignal at the high potential side of the resistor 356 corresponds to thetorque being generated by the motor 232. This motor torque signal isamplified by an amplifier circuit 358, which may be implemented with anoperational amplifier as shown in FIG. 31, and provided to themicrocontroller 342. The microcontroller 342 compares the motor torquesignal to the torque limit signal and generates a torque limitindicating signal in response to the motor torque signal being equal toor greater than the torque limit signal. The torque limit indicatingsignal may have a rectangular waveform.

In one embodiment, the microcontroller 342 provides a torque limitindicating signal that is a rectangular signal having an off-state of atleast 200μ seconds at a frequency of approximately 30 Hz. This torquelimit indicating signal causes the driver circuit 344 to generate motorinterface control signals that disconnect power from the motor 232 andcouple the MOSFETs 348, 350, 352 and 354 together so the current withinthe windings of the motor 232 flows back through the motor 232 todynamically brake the motor 232.

The dynamic braking causes the motor 232 to stop. Before application ofthe next on-state pulse, the microcontroller inverts the signal to thedirection control input of the H-bridge driver 344. Thus, the subsequenton-state of the rectangular pulse causes the H-bridge driver circuit 344to operate the H-bridge to couple the motor 232 to the rechargeablebattery pack 106 with a polarity that is the reverse of the one used tocouple the motor 232 and the rechargeable battery pack 106 prior tobraking. This brake/reverse/start operation of the motor at the 30 Hzfrequency causes the tool to vibrate in a manner that alerts theoperator that the torque limit has been reached while preventing the bitfrom continuing to rotate during the clutching operation. The dynamicbraking may also be used without inverting the signal.

In yet another embodiment, the rectangular waveform may be generated fora fixed duration, for example, 10 to 20 pulses, so the motor is notover-pulsed. Also, the microcontroller 342 may invert the directioncontrol signal to the H-bridge driver 344 during the off-time of therectangular waveform so that the motor 232 starts in the oppositedirection each time. This action results in the net output rotationbeing zero during the clutching duration. Additionally, themicrocontroller 342 may disable the clutching function in response tothe motor direction control signal indicating reverse, rather thanforward, operation of the motor 232.

FIGS. 32A and 32B show an embodiment of a circuit used in a tool thateliminates the need for mechanical contacts. The circuit 360 includes anoptical speed control switch 362, a two position forward/reverse switch364, a microcontroller 366, a driver circuit 368, an H-bridge circuit370, a motor 372, a shunt resistor 374, a motor torque signal amplifier376, and a torque limit signal generator 378. In this embodiment, poweris coupled to the motor 372 through the H-bridge circuit 370, but themain contact, brake contact, and bypass contact are no longer required.Thus, this embodiment significantly reduces the number of componentsthat are subject to mechanical wear and degradation. Because the opticalcontrol switch 362, microcontroller 366, driver circuit 368, H-bridgecircuit 370, and torque signal amplifier 376 may all be implemented withintegrated circuits, then ICs may be mounted on a common printed circuitand the space previously occupied by the mechanical contacts andvariable signal potentiometer are gained. This construction furtherenables the tool components to be arranged in more efficient geometries.

In the circuit 360, the optical speed control switch 362 operates asdescribed above to generate a variable control signal from thereflection of an optical signal directed at the reflective surface of apivoting trigger. The variable speed control signal is provided to themicrocontroller 366 for processing. The microcontroller 366, which maybe a microcontroller available from Texas Instruments and designated bypart number MSP430, is programmed with instructions to generate a PWMpulse with an on-state that corresponds to the level of the variablespeed signal. The microcontroller 366 provides the PWM signal to thedriver circuit 368 for generation of the four motor interface controlsignals used to couple battery power to the motor 372. The direction inwhich the motor 372 is driven is determined by the contacts in the twoposition forward/reverse switch 364 through which a signal is providedto the microcontroller 366. In the circuit 360, the contacts of the twoposition forward/reverse switch 364 do not need to carry the currentprovided to the motor 372 so the contacts of the two positionforward/reverse switch 364 may be smaller than contacts in othersystems. The directional signal is also provided by the microcontroller366 to the driver circuit 368 so the driver circuit 368 is capable oftwo directional control of current in the H-bridge circuit 370.

The motor torque signal amplifier 376 provides the torque signal fromthe high potential side of the shunt resistor 374 to the microcontroller366. The torque limit signal generator 378 may be implemented with apotentiometer as described above to provide a reference signal for themicrocontroller 366. When the microcontroller 366 determines that themotor torque signal equals or exceeds the motor torque limit, themicrocontroller 366 generates a torque limit indicating signal so thedriver circuit 368 generates the motor interface control signals thatoperate the motor 372 in a manner that causes vibration. For the TD340driver circuit, the torque limit indicating signal generated by themicrocontroller 366 is a rectangular signal having an off-state of atleast about 200μ seconds at a frequency of about 30 Hz.

While the present invention has been illustrated by the description ofexemplary processes and system components, and while the variousprocesses and components have been described in considerable detail,applicant does not intend to restrict or in any limit the scope of theappended claims to such detail. Additional advantages and modificationswill also readily appear to those skilled in the art. The invention inits broadest aspects is therefore not limited to the specific details,implementations, or illustrative examples shown and described.Accordingly, departures may be made from such details without departingfrom the spirit or scope of applicant's general inventive concept.

1. An articulating hand power tool comprising: a head portion including,a head housing, a bit holder rotatably positioned within the headhousing, and a bearing member operable to transfer a first axial forcefrom the bit holder to the head housing; a frame rotatably connected tothe head portion for placement in a plurality of positions with respectto the head portion and operably connected to the head housing forreceiving the first axial force transferred to the head housing; and anarticulating gear system for transferring rotational force generated bya motor to the bit holder at each of the plurality of positions.
 2. Thehand power tool of claim 1 wherein the articulating gear systemcomprises a bevel gear with a bevel shaft and the frame is configured asa bearing surface for the bevel shaft.
 3. The hand power tool of claim2, further comprising: a thrust bearing located between the frame andthe bevel gear.
 4. The hand power tool of claim 1, further comprising: avariable speed trigger switch operably connected to the motor forvariably controlling the speed of the motor and movable within a planebetween a first position corresponding to a first motor speed and asecond position corresponding to a second motor speed; and a fingerplatform located within the plane adjacent to the variable speed triggerswitch.
 5. The hand power tool of claim 1, further comprising: acylinder pin positioned within the bit holder for receiving the firstaxial force from a bit positioned within the bit holder and operable totransfer the first axial force from the bit to the bit holder.
 6. Thehand power tool of claim 5, further comprising: an outer housing forreceiving at least a portion of the frame and operably connected to theframe such that the first axial force received by the frame istransferred to the housing.
 7. The hand power tool of claim 1, furthercomprising: an outer housing for receiving at least a portion of theframe; and an articulation button movable between a first positionwherein the articulation button contacts the outer housing and the headhousing so as to restrict rotation of the head housing with respect tothe outer housing and a second position wherein the articulation buttondoes not restrict rotation of the head housing with respect to the outerhousing.
 8. The hand power tool of claim 7, wherein: the bearing memberis operable to transfer a second axial force from the bit holder to thehead housing; and the articulation button is configured to transfer thesecond axial force from the head housing to the outer housing.
 9. Thehand power tool of claim 7, wherein: the head housing comprises a firstplurality of teeth; the articulation button comprises a second pluralityof teeth; and the outer housing comprises a third plurality of teeth,wherein the second plurality of teeth is engaged with both the firstplurality of teeth and the third plurality of teeth when thearticulation button is in the first position and the second plurality ofteeth is engaged with only one of the first plurality of teeth and thethird plurality of teeth when the articulation button is in the secondposition.
 10. The hand power tool of claim 1 wherein the head housing isconfigured to restrict an output pinion gear of the articulating gearsystem from movement in a direction away from a bevel gear of thearticulating gear system, the head portion further comprising: a bracketattached to the head housing for providing radial support to the outputpinion gear at a location between the pinion gear and the bevel gear.11. The hand power tool of claim 1, further comprising: an outer housingengaged with the head housing and configured to receive and support atleast a portion of the frame; a gap in the portion of the head housingsurrounding the articulating gear system, which allows the head housingto be rotated with respect to the outer housing; and a dust lid which isconfigured to be wider than the gap to restrict access from outside ofthe hand power tool to the articulating gear system.
 12. The hand powertool of claim 1, further comprising: a gap defined by the head housingand sized to receive a portion of the frame therethrough; and a dust lidlocated adjacent the gap for restricting access through the gap.
 13. Thehand power tool of claim 1, further comprising: an outer housing engagedwith the head housing and configured to receive and support at least aportion of the frame; a channel located between the head housing and theouter housing; and a dust lid configured to fit slidingly within thechannel.
 14. The hand power tool of claim 13, further comprising: afirst dust lid travel limiter on the head housing configured to move thedust lid within the channel as the frame rotates with respect to thehead portion from a first of the plurality of positions to a second ofthe plurality of positions; and a second dust lid limiter on the outerhousing configured to prevent movement of the dust lid past the seconddust lid limiter as the frame rotates with respect to the head portionfrom the first of the plurality of positions to a third of the pluralityof positions, the third of the plurality of positions and the second ofthe plurality of locations located on opposite sides of the first of theplurality of positions.
 15. The hand power tool of claim 13, furthercomprising: an articulation detent system including a spring loaded,toothed button which interfaces with mating toothed pockets in the headhousing and the outer housing in a locked or unpressed position andwhich interfaces only with the head housing in an unlocked or pressedposition thus allowing movement or rotation of the head portion relativeto the outer housing, the detent system being concentric with a bevelgear of the articulating gear system.
 16. The hand power tool of claim1, wherein the articulating gear system comprises: a motor side piniongear, an output side pinion gear; and a bevel gear having a first sideengaged with the power side pinion gear and the output side pinion gearand a second side supported by a thrust bearing.
 17. The hand power toolof claim 16, wherein the thrust bearing is made from an oil impregnatedbronze.
 18. A method of transferring axial forces in an articulatingpower tool comprising: transferring an axial force from a bit holderrotatably positioned within a head housing of a tool to a bearingmember; transferring the axial force from the bearing member to the headhousing; and transferring the axial force from the head housing to amain housing, wherein the head housing is rotatable with respect to themain housing.
 19. The method of claim 18, further comprising:transferring an axial force from a bit to a cylinder pin located withinthe bit holder.
 20. The method of claim 18, wherein transferring theaxial force from the head housing to a main housing comprises:transferring the axial force from the head housing to a frame at leastpartially received within the main housing; and transferring the axialforce from the frame to the main housing.
 21. The method of claim 18,wherein transferring the axial force from the head housing to a mainhousing comprises: transferring the axial force from the head housing toan articulation button; and transferring the axial force from thearticulation button to the main housing.
 22. The method of claim 18,wherein transferring the axial force from the head housing to a mainhousing comprises: transferring a first portion of the axial force fromthe head housing to a frame at least partially received within the mainhousing; transferring the first portion of the axial force from theframe to the main housing; transferring a second portion of the axialforce from the head housing to an articulation button; and transferringthe second portion of the axial force from the articulation button tothe main housing.